a) To find the 39th percentile:
1. Order all the values in the data set from smallest to largest:
[tex]9,13,13,13,16,17,19,21,23,26,28,29,31,33,36,37,37,38,39,40,40,43,44,46,49[/tex]2. Multiply 39% by the total number of values:
[tex]\frac{39}{100}*25=9.75[/tex]3. Round the number you get in previous step to the nearest whole number:
[tex]9.75\approx10[/tex]4. The data in the 10th position (ordered values) is the 39th percentile.
39th percentile: 26
The 39th percentile is the data value 26b) To find the 78th percentile:
1. Use the ordered values you get above:
[tex]9,13,13,13,16,17,19,21,23,26,28,29,31,33,36,37,37,38,39,40,40,43,44,46,49[/tex]2. Multiply 78% by the total number of values:
[tex]\frac{78}{100}*25=19.5[/tex]3. Round the number you get in previous step to the nearest whole number:
[tex]19.5\approx20[/tex]4. The data in the 20th position (ordered values) is the 78th percentile.
78th percentile: 40
The 78th percentile is the data value 40